31076 Results for "C"

Humans Make Up For Vitamin C Shortfall

—Humans Make Up For Vitamin C Shortfall “” More than 4,000 mammals can make vitamin C from glucose, but the human version of the necessary enzyme is out of order. To make up for our species' incompetence, humans have evolved a way to efficiently utilize the vitamin C we consume. In particular, researchers led by Naomi Taylor at the National Center for Scientific Research, in Montpellier, France, show that a glucose transport protein on the surface of human red blood cells is altered by another protein called stomatin so that vitamin C's oxidized form, L-dehydroascorbic acid (DHA, shown above right), is preferentially imported into red blood cells instead of glucose (Cell 2008, 132, 1039). DHA is then quickly reduced to vitamin C inside the blood cells. In fact, humans express three orders of magnitude more of these glucose-turned-DHA transporters on their red blood cells than do mammals that produce their own vitamin C. Because of this efficient vitamin C cycling, humans need only consume 1 mg of vitamin C per kg of body weight per day, whereas goats have to synthesize 200 times that amount. /articles/86/i13/Humans-Make-Vitamin-C-Shortfall.html 20080331 Concentrates 86 13 /magazine/86/8613.html Humans Make Up For Vitamin C Shortfall con scitech biological-chemistry Humans Make Up For Vitamin C Shortfall Chemical & Engineering News Humans Make Up For Vitamin C Shortfall Humans Make Up For Vitamin C Shortfall

March 31, 2008

Herbert C. Brown Award for Creative Research in Synthetic Methods: Gregory C. Fu

—Herbert C. Brown Award for Creative Research in Synthetic Methods: Gregory C. Fu “” Sponsor: Purdue Borane Research Fund and the Herbert C. Brown Award Endowment Citation: For the development of nickel- and copper-catalyzed cross-coupling methods and of nucleophile-catalyzed enantioselective reactions.

January 08, 2018

Chemists untangle metal-free C–C coupling reactions

—Chemists untangle metal-free C–C coupling reactions “Radical versus cationic pathway depends on electron-hogging nature of functional groups” Most reactions that make new carbon-carbon bonds need some kind of transition-metal catalyst. Because these metals can be toxic, scientists want to ditch them, especially when synthesizing pharmaceutical compounds.

by Leigh Krietsch Boerner | March 20, 2021

Strong, aliphatic C–H bonds succumb to direct arylation

A decatungstate catalyst generates carbon-centered radicals from strong, neutral C–H bonds. These radicals then act as nucleophiles in nickel-mediated cross-coupling with aryl bromides, forging C(sp3)–C(sp2) bonds between the aliphatic and aryl groups. “You go into this thinking it’s going to be an unholy mess, but it turns out it’s exquisitely selective,” MacMillan says, adding that the group can predict with 95% accuracy which C–H bond will react. The C–H bond that reacts must yield a stable radical and that radical must be able to attach to the nickel and participate in reductive elimination with the metal. “The direct cross-coupling of unactivated, aliphatic C–H bonds is one of those transformations that synthetic chemists dream about,” comments Erik Alexanian, an organic chemist who studies aliphatic C–H functionalization at the University of North Carolina, Chapel Hill.

by Bethany Halford | August 01, 2018

Redesigned And Refocused

—Redesigned And Refocused “” On this week's issue date, March 29, C&EN Online launched a completely redesigned home page. C&EN Online debuted in August 1998, and the home page has been redesigned several times, as is common in the online world. This redesign, however, is by far the most significant in the six-year history of C&EN Online because, with it, we have completely refocused our approach to bringing you breaking news of the chemical enterprise. Since C&EN is a weekly news magazine, when we launched C&EN Online, it conformed entirely to the weekly rhythm of the print magazine. C&EN Online then had a staff of one--Online Editor Melody Voith. It was her full-time job to post the editorial content of C&EN on the Web each week, augmented with a rich array of links to ACS journal articles and business, government, and academic websites.

by Rudy M. Baum | March 29, 2004

DSM Will Buy Chinese Vitamin C Producer

—DSM Will Buy Chinese Vitamin C Producer “” DSM has agreed to acquire the Chinese vitamin C producer Aland. Listed on the Hong Kong Stock Exchange, Aland employs 1,850 people and operates a plant in Jingjiang, Jiangsu province. It recorded vitamin C sales of $90 million in 2013. DSM, which disclosed talks about the acquisition in April, is not buying Aland’s consumer health business. The Dutch company says it remains fully committed to its current vitamin C facility in Dalry, Scotland. Vitamin C is the world’s largest-volume vitamin. /articles/92/i29/DSM-Buy-Chinese-Vitamin-C.html 20140721 Concentrates 92 29 /magazine/92/09229.html DSM Will Buy Chinese Vitamin C Producer vitamin C, China con bus Jean-François Tremblay business DSM Will Buy Chinese Vitamin C Producer Chemical & Engineering News DSM Will Buy Chinese Vitamin C Producer DSM Will Buy Chinese Vitamin C Producer

by Jean-François Tremblay | July 21, 2014

Dual C–F/C–H functionalization unveiled

—Dual C–F/C–H functionalization unveiled “Iridium photocatalyst enables coupling of two unactivated aryl partners to create complex multifluorinated biaryl compounds” In an effort to develop a general method for making multifluorinated biaryl compounds, a pair of chemists has achieved the first example of a direct cross-coupling reaction between a C–F bond of one aryl compound and a C–H bond of another aryl compound without having to first prefunctionalize either of the aryl coupling partners like in traditional cross-coupling strategies (J.

by Stephen K. Ritter | March 07, 2016

C&EN Earns Top Publishing Prizes

Innovation At C&EN

Another important innovation was launched on Monday of this week, the permanent C&EN blog, "C&ENtral Science," which you can access from the home page of C&EN Online at www.cen-online.org or directly at www.cenblog.org. C&EN has had episodic blogs previously, associated with ACS national meetings and other events.

by Rudy Baum | March 31, 2008